Successes in diagnosis and treatment of cancer have resulted in dramatic increases in the number of long- term cancer survivors. In fact, the past 20 years has seen dramatic shifts in patients receiving care in primary care practices like cancer survivors with complex, co-morbid conditions. Instead of most visits being for acute or single chronic conditions, the majority of visits are now for patients with complex conditions and needs. To meet the needs of complex patients like cancer survivors, primary care practices must radically reconfigure. The Patient-Centered Medical Home (PCMH) is purported to enhance quality and safety in primary care and is often part of health system reform efforts. While much is written about the PCMH, it is not clear that a PCMH enhances quality for complex patients like cancer survivors. In fact, PCMH attributes critical for meeting the needs of cancer survivors are the most challenging to implement: reorienting to a population perspective, developing collaborative teams, integrating healthcare neighborhoods and community resources, and changing roles/identities of clinicians and staff. Complexity science (CS) provides a theoretical basis for understanding how primary care practices implement innovations like the PCMH. As complex adaptive systems, practices self-organize according to dominant goals and co-evolve to take on configurations consistent with those goals. If a goal of achieving NCQA recognition dominates, practices self-organize to maximize this goal. Likewise, if caring for individuals, families, and communities dominates, practices self-organize to maximize this goal. In both cases, the result may be a PCMH, but CS suggests they might evolve to have very different capacities to care for cancer survivors. To identify and describe how PCMHs successfully implement the challenging attributes needed for cancer survivor care, we use a CS framework to conduct comparative case studies of practices that used different PCMH implementation strategies: some focused on NCQA Level 3 PCMH recognition and others focused on caring for individuals, families, and communities. We examine innovative primary care practices using a mixed- methods comparative case study design with practices selected from a national list of innovative practices. An initial sample of 10 practices (5 seeking level 3 NCQA recognition and 5 seeking to meet needs of individuals, families, and communities) will be selected for comparative purposes, with 10 replicative cases selected to confirm/disconfirm hypotheses. Data include validated surveys, costs of implementing and sustaining innovations, and ethnographic observations and interviews of practice members and patients. Results could have a profound impact on cancer survivor care and PCMH implementation strategies used throughout the US.